Formation of reactive oxygen metabolites is vital for the microbicidal activity of phagocytes. As an unwanted side effect, these metabolites may contribute to oxidative stress in the vasculature and thus lead to arteriosclerosis. p22 phox, a component of the NADH/NADPH oxidase in phagocytes and vascular smooth muscle cells, is essential for production of reactive oxygen metabolites. Recently, a C/T polymorphism at position 242 of the p22 phox gene has been associated with coronary artery disease (CAD), suggesting a protective effect of the 242 T allele on the vasculature. In the present study, we analysed the relation of this polymorphism to peripheral arterial occlusive disease (PAOD). C242T polymorphism was determined by restriction fragment polymorphism (RFLP) analysis in 324 patients with documented PAOD and 295 control subjects without any known arterial disease. p22 phox 242 T allele frequencies and genotype distributions were not significantly different between patients and controls; the adjusted relative risk associated with the 242 T allele was 1.14 (95% CI 0.84-1.54, P=0.39), assuming an additive effect of the T allele. C242T polymorphism was not associated with the age of patients at the onset of the disease. Our data indicate that C242T polymorphism of the p22 phox gene is not associated with PAOD.